Adding functional model in Python. Used to drive RTL development.

1 files changed, 222 insertions, 0 deletions

diff --git a/src/model/python/sha1.py b/src/model/python/sha1.py
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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#=======================================================================
+#
+# sha1.py
+# ---------
+# Simple, pure Python model of the SHA-1 function. Used as a
+# reference for the HW implementation. The code follows the structure
+# of the HW implementation as much as possible.
+#
+#
+# Author: Joachim Strömbergson
+# (c) 2014 SUNET
+# 
+# Redistribution and use in source and binary forms, with or 
+# without modification, are permitted provided that the following 
+# conditions are met: 
+# 
+# 1. Redistributions of source code must retain the above copyright 
+#    notice, this list of conditions and the following disclaimer. 
+# 
+# 2. Redistributions in binary form must reproduce the above copyright 
+#    notice, this list of conditions and the following disclaimer in 
+#    the documentation and/or other materials provided with the 
+#    distribution. 
+# 
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
+# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
+# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+#=======================================================================
+
+#-------------------------------------------------------------------
+# Python module imports.
+#-------------------------------------------------------------------
+import sys
+
+
+#-------------------------------------------------------------------
+# Constants.
+#-------------------------------------------------------------------
+
+
+#-------------------------------------------------------------------
+# ChaCha()
+#-------------------------------------------------------------------
+class SHA1():
+    def __init__(self, verbose = 0):
+        self.verbose = verbose
+        self.H = [0] * 5
+        self.T = 0
+        self.a = 0
+        self.b = 0
+        self.c = 0
+        self.d = 0
+        self.e = 0
+        self.W = [0] * 80
+        self.k = 0
+
+        
+    def init(self):
+        self.H = [0x67452301, 0xefcdab89, 0x98badcfe,
+                  0x10325476, 0xc3d2e1f0]
+        
+
+    def next(self, block):
+        self._W_schedule(block)
+        self._copy_digest()
+        for i in range(80):
+            self._sha1_round(i)
+        self._update_digest()
+
+
+    def get_digest(self):
+        return self.H
+
+
+    def _copy_digest(self):
+        self.a = self.H[0] 
+        self.b = self.H[1] 
+        self.c = self.H[2] 
+        self.d = self.H[3] 
+        self.e = self.H[4] 
+    
+    
+    def _update_digest(self):
+        self.H[0] = (self.H[0] + self.a) & 0xffffffff 
+        self.H[1] = (self.H[1] + self.b) & 0xffffffff 
+        self.H[2] = (self.H[2] + self.c) & 0xffffffff 
+        self.H[3] = (self.H[3] + self.d) & 0xffffffff 
+        self.H[4] = (self.H[4] + self.e) & 0xffffffff 
+
+
+    def _sha1_round(self, round):
+        if round <= 19:
+            self.k = 0x5a827999        
+            self.f = self._Ch(self.b, self.c, self.d)
+
+        elif 20 <= round <= 39:
+            self.k = 0x6ed9eba1
+            self.f = self._Parity(self.b, self.c, self.d)
+
+        elif 40 <= round <= 59:
+            self.k = 0x8f1bbcdc
+            self.f = self._Maj(self.b, self.c, self.d)
+
+        elif 60 <= round <= 79:
+            self.k = 0xca62c1d6
+            self.f = self._Parity(self.b, self.c, self.d)
+
+        if self.verbose:
+            print("Round %0d" % round)
+            print("Round input values:")
+            print("a = 0x%08x, b = 0x%08x, c = 0x%08x" % (self.a, self.b, self.c))
+            print("d = 0x%08x, e = 0x%08x" % (self.d, self.e))
+            print("f = 0x%08x, k = 0x%08x, w = 0x%08x" % (self.f, self.k, self.W[round]))
+            
+        
+        self.T = (self._rotl32(self.a, 5) + self.f + self.e + self.k + self.W[round]) & 0xffffffff
+        self.e = self.d
+        self.d = self.c
+        self.c = self._rotl32(self.b, 30)
+        self.b = self.a
+        self.a = self.T
+
+        if self.verbose:
+            print("Round output values:")
+            print("a = 0x%08x, b = 0x%08x, c = 0x%08x" % (self.a, self.b, self.c))
+            print("d = 0x%08x, e = 0x%08x" % (self.d, self.e))
+            print("")
+
+
+    def _W_schedule(self, block):
+        # Expand the block into 80 words before round operations.
+        for i in range(80):
+            if (i < 16):
+                self.W[i] = block[i]
+            else:
+                self.W[i] = self._rotl32((self.W[(i - 3)] ^ self.W[(i - 8)] ^
+                                          self.W[(i - 14)] ^ self.W[(i - 16)]), 1)
+        if (self.verbose):
+            print("W after schedule:")
+            for i in range(80):
+                print("W[%02d] = 0x%08x" % (i, self.W[i]))
+            print("")
+
+
+    def _Ch(self, x, y, z):
+        return (x & y) ^ (~x & z)
+
+
+    def _Maj(self, x, y, z):
+        return (x & y) ^ (x & z) ^ (y & z)
+
+
+    def _Parity(self, x, y, z):
+        return (x ^ y ^ z)
+
+    def _rotl32(self, n, r):
+        return ((n << r) | (n >> (32 - r))) & 0xffffffff
+
+
+def compare_digests(digest, expected):
+    if (digest != expected):
+        print("Error:")
+        print("Got:")
+        print(digest)
+        print("Expected:")
+        print(expected)
+    else:
+        print("Test case ok.")
+        
+    
+#-------------------------------------------------------------------
+# main()
+#
+# If executed tests the ChaCha class using known test vectors.
+#-------------------------------------------------------------------
+def main():
+    print("Testing the SHA-256 Python model.")
+    print("---------------------------------")
+    print
+
+    my_sha1 = SHA1(verbose=1);
+
+    # TC1: NIST testcase with message "abc"
+    TC1_block = [0x61626380, 0x00000000, 0x00000000, 0x00000000, 
+                 0x00000000, 0x00000000, 0x00000000, 0x00000000,
+                 0x00000000, 0x00000000, 0x00000000, 0x00000000,
+                 0x00000000, 0x00000000, 0x00000000, 0x00000018]
+    
+    TC1_expected = [0xa9993e36, 0x4706816a, 0xba3e2571,
+                    0x7850c26c, 0x9cd0d89d]
+    
+    my_sha1.init()
+    my_sha1.next(TC1_block)
+    my_digest = my_sha1.get_digest()
+    compare_digests(my_digest, TC1_expected)
+
+    
+
+#-------------------------------------------------------------------
+# __name__
+# Python thingy which allows the file to be run standalone as
+# well as parsed from within a Python interpreter.
+#-------------------------------------------------------------------
+if __name__=="__main__": 
+    # Run the main function.
+    sys.exit(main())
+
+#=======================================================================
+# EOF sha1.py
+#=======================================================================